[w4]

> Might be possible to do an end-run via the same mechanisms that allow "for sale by owner".

I can't speak universally for every state (there's 50 different sets of regulations, after all), but no. The carve out for FSBO is predicated on selling your own home. If you're facilitating the sale or rental of someone else's home, it triggers the licensing requirements.

[JoshTriplett]

Not what I mean. There are several services that provide materials and kits for doing such a sale; Zillow could let the owner control the sale, but provide services to the owner rather than sitting in the middle.

[w4]

Ah, gotcha. I misunderstood what you meant. You can definitely offer limited services and advertising. You just have to be very careful not to engage in any activities the state might construe as creating an agency relationship, or that are specifically reserved for licensed agents.